Appearance
Bradford pear is a cultivar of Pyrus calleryana. It is a deciduous tree that can grow up to 60 ft. (18 m) in height and 2 ft. (0.6 m) in diameter.

Foliage
The leaves are alternate, simple, 2-3 in. (5.1-7.6 cm) long, petiolate, and shiny with wavy, slightly toothed margins.

Flower
Flowering occurs early in the spring (April to May) before the leaves emerge. The flowers are 1 in. (2.5 cm) wide, showy, malodorous, and white. It is insect pollinated.

Fruit
Fruits are round, 0.5 in. (1.3 cm) in diameter, and green to brown in color.

Ecological Threat
Pyrus calleryana 'Bradford', produces sterile fruits because they do not self-pollinate. They have been widely planted throughout the United States since the early 1960s as ornamental. New cultivars of Pyrus calleryana were bred to reduce the tree's tendency to split in snow or high winds. The Bradford pear cultivar, other P. calleryana cultivars, and P. betulifolia or Asian pear, can hybridize and produce fertile fruit. In addition to this, fertile pear varieties are commonly used as rootstock when grafting. If the grafted crown is damaged the fertile rootstock can dominate, producing fertile fruit. These factors and others may have contributed to the trees seeding out into natural areas and becoming an invasive problem.

Resources

• Weed of the Week - USDA Forest Service
• Plant Invaders of Mid-Atlantic Natural Areas - National Park Service and U.S. Fish and Wildlife Service

Selected Images

Maps

Invasive Listing Sources

• Alabama Invasive Plant Council
• California Invasive Plant Council
• City of Ann Arbor Michigan Parks and Recreation
• Commonwealth of Pennsylvania, Department of Conservation and Natural Resources, 1994.
• Connecticut Invasive Plant List
• Connecticut Invasive Plant Working Group
• Delaware Invasive Species Council
• Delaware Invasive Species Council Invasive Species List
• Georgia Exotic Pest Plant Council - Category 3
• Indiana Invasive Species Council - Invasive Plant List
• Invasive Plant Species of West Virginia
• Kentucky Exotic Pest Plant Council - Severe Threat
• Maine Invasive Plants
• Maryland Code and Regulations of Invasive Plants
• Maryland Cooperative Extension Service.  2003. Invasive Plant Control in Maryland. Home and Garden Information Center, Home and Garden Mimeo HG88. 4 pp.
• Maryland Department of Natural Resources Policy: Restriction on Planting Exotic Invasive Plants
• Maryland Invasive Species Council - Invasive Species of Concern in Maryland
• Massachusetts Invasive Plants Advisory Group List
• Massachusetts Noxious Weeds
• Minnesota Noxious Weeds
• Missouri SRISP Species List
• National Park Service, Mid-Atlantic Exotic Plant Management Team Invasive Plant List
• Native Plant Society of Oregon, 2008
• New Hampshire Invasive Species Committee. 2005. Guide to Invasive Upland Plant Species in New Hampshire. New Hampshire Department of Agriculture,  Markets and Food Plant Industry Division and New Hampshire Invasive Species Committee.
• New Jersey Invasive Species Strike Team 2017 Invasive Species List
• Non-Native Invasive Plants of Arlington County, Virginia
• Non-Native Invasive Plants of the City of Alexandria, Virginia
• Nonnative Invasive Species in Southern Forest and Grassland Ecosystems
• Ohio Invasive Species Council
• Pennsylvania Department of Conservation and Natural Resources Invasive Plants
• Pennsylvania Noxious Weeds
• Plant Invaders of Mid-Atlantic Natural Areas
• Rhode Island Natural History Survey
• South Carolina Invasive Pest Council
• South Carolina Plant Pest List
• Tennessee Exotic Pest Plant Council
• Virginia Invasive Plant Species List
• Virginia Master Naturalists Priority Species List
• WeedUS - Database of Plants Invading Natural Areas in the United States
• West Virginia Invasive Species Strategic Plan and Volunteer Guidelines 2014
• West Virginia Native Plant Society, Flora West Virginia Project, and West Virginia Curatorial Database System, September 3, 1999

References